Smile and move forward. If they are not able to forget the mistakes of the past, then that is their problem.
You should forget the mistakes of the past, just drop it and move ahead.
You are not the same person as you were in the past when you committed those mistakes, you have changed. When you came to the spiritual path, when you gained this wonderful knowledge, then your entire life has changed.
So have complete and unshakeable faith in this fact.
In the ancient times, when people used to approach a Guru, then they would even change their birth names.
Why was this done? It was to signify that you have taken a new birth altogether when you have come to the Guru.
You have become a new person when you gained access to this knowledge.
The mistakes you committed in the past out of ignorance do not exist anymore in light of the knowledge you have now received.
Ignorant people around you may sometimes do such things, but you should have compassion for them instead of feeling hurt or angry. Think that,
“Oh, they are still stuck and do not know that I am a totally different person now. I have changed”.
This faith you must develop in yourself. There is no need to fall into self-pity.